Broadband and wide dynamic-range seismological observations (STS-1) started at Syowa Station (69S, 39E) in 1989 as one of the Federation of Digital Seismographic Network (FDSN). The shear wave velocity structure and the splitting parameters in the crust and the uppermost-mantle in the Lützow-Holm Bay region were analyzed using digital seismogram waveform data (e.g., Kubo et al., 1995). These methods, however, can only obtain information on the crustal structure just beneath the station site. On the other hand, the existence of crustal heterogeneity beneath the Lützow-Holm Bay region has been suggested, based on various geoscientific surveys. The azimuthal variations of the shear wave velocity structure beneath Syowa Station using teleseismic receiver functions (Kanao, 1997). The receiver function analysis, however, could not clarify the detailed heterogeneous structure around the area. Therefore, field observations at several outcrops with the broadband seismometer are needed to clarify the crustal heterogeneity and to investigate the crustal evolution of the wide areas of Antarctic continent.
Field observations by broadband seismometers have been carried out from 1996 at several outcrops around the Lützow-Holm Bay region, East Antarctica. Recording system was composed of a portable broadband seismometer, a digital recording unit and a solar power supply. Expect for power supply failure in dark winter seasons, the observations have been conducted and significant number of teleseismic events were recorded. These data are utilized for seismological analyses to clarify heterogeneous structure of the Earth, particularly around the Antarctic polar region. Obtained data have advantages not only to the crust - upper mantle studies but also to deep Earth's interior such as the CMB and D" zones, by applying as a large span array stations in southern high latitude. These observations can give efficient cooperatives to the Global Alliance of Regional Networks (GARNET) proposed by the National Research Institute for Earth Science and Disaster Prevention (NIED).
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